It takes a number of the following strategies.
An ideal way to do this is with a combination of weight-bearing activities (tennis, stair climbing, or an activity that involves jumping, like an aerobic workout or dancing) and strength training (in which you work your muscles against resistance, such as free weights, resistance bands, or your own body weight).
Get clearance from your doctor before exercising, and work with a physical therapist to develop a program tailored to your needs. Aim for 150 minutes of moderate-intensity exercise per week for cardiovascular health
Get enough calcium and vitamin D
Calcium helps make strong bones, and vitamin D aids calcium absorption. Take a daily vitamin D3 supplement (D3 is the form most easily absorbed) between 600 to 1,000 IU, depending on your blood levels of vitamin D. Consult with you physician.
Medications called bisphosphonates, such as alendronate (Fosamax), help slow the rate of bone loss. They're typically prescribed for someone with osteopenia who is deemed to be at high risk for fracture, someone who has osteoporosis, or someone who has already had a fracture from a fall. Consult with your physician.
Make lifestyle changes
Smoking and excessive alcohol use can interfere with bone health. So quit smoking, and limit alcohol intake (no more than one drink per day for women, two drinks for men.
“While adequate intake of calcium and vitamin D are considered important for bone health, a growing number of studies show a strong association between exercise and improvements in bone mineral density—the amount of calcium in the bone. Because bone is living tissue, it responds to exercise by becoming stronger and denser.” Laura Landro